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bbl232

Member

Registered: 2016-02-18

Posts: 3

PCI Passthrough VS VGA Passthrough

I have a win10 VM set up on an amd host that uses the graphics card that I have passed through via PCI (using virt-manager) only AFTER windows has booted. If I reboot the machine, I have to remove the device and add it again before the VM will start to use the card again.

I have attached the XML for my machine below

<domain type='kvm' xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'>
  <name>win10</name>
  <uuid>8dd2b4bf-5da1-4531-ad2f-6439e767de11</uuid>
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <vcpu placement='static'>2</vcpu>
  <os>
    <type arch='x86_64' machine='pc-i440fx-2.5'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <kvm>
      <hidden state='on'/>
    </kvm>
    <vmport state='off'/>
  </features>
  <cpu mode='host-model'>
    <model fallback='allow'/>
  </cpu>
  <clock offset='localtime'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <pm>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
  </pm>
  <devices>
    <emulator>/usr/sbin/qemu-system-x86_64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='raw'/>
      <source file='/var/lib/libvirt/images/Windows-1.img'/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='ich9-ehci1'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x7'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci1'>
      <master startport='0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0' multifunction='on'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci2'>
      <master startport='2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x1'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci3'>
      <master startport='4'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>
    <interface type='direct'>
      <mac address='52:54:00:d2:77:c4'/>
      <source dev='enp2s0' mode='bridge'/>
      <model type='rtl8139'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <input type='tablet' bus='usb'/>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' autoport='yes'/>
    <sound model='ich6'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </sound>
    <video>
      <model type='cirrus' vram='16384' heads='1'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <hostdev mode='subsystem' type='usb' managed='yes'>
      <source>
        <vendor id='0x2516'/>
        <product id='0x0011'/>
      </source>
    </hostdev>
    <hostdev mode='subsystem' type='usb' managed='yes'>
      <source>
        <vendor id='0x045e'/>
        <product id='0x0745'/>
      </source>
    </hostdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
    </redirdev>
    <memballoon model='virtio'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </memballoon>
  </devices>
  <qemu:commandline>
    <qemu:arg value='-vga'/>
    <qemu:arg value='none'/>
  </qemu:commandline>
</domain>

Note that if the card is attached to the machine before it has booted the card reports code 43 in the device manager.
The card is a GeForce GT 620 512mb

Anyone have any ideas on how to work around this?

I have a feeling it has something to do with PCI passthrough vs VGA passthrough which I could not get to work following several tutorials (a lot of them seem outdated).

Last edited by bbl232 (2016-02-18 22:23:04)

headkase

Member

Registered: 2011-12-06

Posts: 1,986

Re: PCI Passthrough VS VGA Passthrough

I believe you have to hide the KVM hypervisor signature.  If a nVidia card detects it is running under virtualization it will disable itself unless it is a Quadro or other type professional card.  That is what I recall anyway.

bbl232

Member

Registered: 2016-02-18

Posts: 3

Re: PCI Passthrough VS VGA Passthrough

I have actually done that using

<kvm>
      <hidden state='on'/>
</kvm>

Thanks

bbl232

Member

Registered: 2016-02-18

Posts: 3

Re: PCI Passthrough VS VGA Passthrough

I have gotten this working using an old AMD card, I'll just buy a new card to stick in there. Thanks